HIV infection rates have increased in the United States to epidemic levels, and many of these new infections occur in adolescents (CDC, 2009). Engaging in risk-taking behaviors such as substance use puts adolescents at heightened risk for HIV infection (Leigh & Stall, 1993). Neurological and environmental reasons have been suggested for this increased risk taking in adolescence: (a) regions of adolescents' brains develop at different rates, affecting their abilities to regulate their actions and in particular assess risks and rewards for engaging in specific behaviors (e.g,, substance use, unprotected sexual intercourse; Geier, Terwilliger, Teslovich, Velanova, & Luna, 2010l Steinberg, 2007); and (b) family-level precursors such as parent-adolescent conflict have been significantly associated with and may pose risk for engaging in substance use and risk-taking (Duncan, Duncan, Biglan, & Ary, 1998). Thus, parent-adolescent conflict may be an important proximal influence in HIV risk behaviors (Lam, Cance, Eke, Fishbein, Hawkins, Williams, 2007; Lester et al., 2010; Rowe, Wang, Greenbaum, & Liddle, 2008). Yet, the temporal relation between parent-adolescent conflict and adolescent HIV risk behaviors is still unknown. Further, it is possible there is a profile of adolescents for whom this conflict increases the likelihood of HIV risk behaviors. To investigate the role of parent-adolescent conflict in HIV risk behaviors, adolescents will be randomly assigned with their parent to complete a standardized discussion task in which they discuss either a control topic (i.e., planning a family vacation) or a conflict topic (i.e., discusing a topic at home that arouses parent-adolescent conflict such as doing chores). Immediately after the discussion task, all adolescents will complete a laboratory risk-taking measure. Adolescents will also complete a self-report measure of real-world risk taking behaviors. The primary aims of the proposed research are to determine if there is a causal link between parent-adolescent conflict and risk-taking behaviors and to identify the factors related to parent-adolescent conflict and HIV risk behaviors for adolescents who score high on the performance-based risk-taking measure. Current substance use is hypothesized to be a moderator of the relation between conflict and risk behaviors. As an exploratory follow-up and with a subsample of adolescents identified as current substance users, investigate the cortical brain regions that moderate the relation between parent-adolescent conflict and risk behaviors using a functional near-infrared spectroscopy device. Training goals for this award are to gain a solid foundation in the conceptualization, development, and neurobehavioral underpinnings of adolescent risk taking, reward processes, and addictions; develop a background in multi-method assessments of family level precursors for HIV risk behaviors; and develop a background in neuroimaging methods.